This invention relates to an interlock for switches, and more particularly pertains to an interlock for two switch members in an electrical panel for preventing both switch members from being in an ON position at the same time.
In an electrical supply system, it is known to provide an alternate source of electrical power in order to supply power to an electrical load in the event of a power outage. For example, in a system in which the primary power supply is utility power, it is desirable to supply power from an alternate source, such as a generator, to continue an uninterrupted power supply to the electrical load in the event of a power outage. When supplying an alternate source of power in this manner, it is known to connect the alternate power supply to a circuit breaker-type switching mechanism. The primary power supply is also interconnected with a circuit breaker-type switching mechanism, and each switching mechanism includes a switch member movable between an ON position and OFF position for controlling connection of utility power and power from the alternate source to the electrical load.
In one arrangement, the switch mechanisms are aligned with each other and the switch members are movable toward each other to an ON position and away from each other to an OFF position. A linkage-type interlock mechanism is interposed between the switch members for preventing both switch members from being in the ON position at the same time. An example of this type of interlock is shown in Flegel U.S. Pat. No. 5,648,646 issued Jul. 15, 1997, the disclosure which is hereby incorporated by reference. Other interlocks of this type are illustrated in Flegel U.S. Pat. 6,096,986 issued Aug. 1, 2000 and U.S. Pat. No. 6,031,193 issued Feb. 29, 2000, the disclosures of which are hereby incorporated by reference.
In another form, the primary power supply, such as utility power, is interconnected with a switch mechanism having a switch member movable in a first direction, and power from an alternate source such as a generator, is supplied to a switch mechanism having a switch member which moves in a direction transverse to that of the switch member of the utility power supply switch mechanism. In a situation such as this, a transverse interlock mechanism is interconnected with the utility power supply switch mechanism and the generator power supply switch mechanism. An interlock of this type is shown and described in Flegel U.S. Pat. No. 6,184,595 issued Feb. 6, 2001, the disclosure which is hereby incorporated by reference.
Some electrical panels or load centers include a primary power supply switch mechanism which utilizes a switch member movable in a back and forth manner in the same direction as the switch member of the auxiliary or generator power supply switch mechanism, and in which the switch members are offset from each other. An interlock is provided to prevent the primary power supply and generator power supply switch mechanisms from being in the ON position simultaneously. An interlock of this type is shown and described in Taylor U.S. Pat. No. 5,977,492 issued Nov. 2, 1999.
It remains desirable to provide an interlock mechanism which prevents two circuit breakers in parallel offset relation to each other, and possibly of different sizes, from being turned ON simultaneously. It is also desirable that the interlock mechanism permits both of the circuit breakers to be switched OFF at the same time.
Accordingly, it is an object of the present invention to provide an improved switch interlock which is adapted for use with switch members which are offset from each other and movable in parallel directions. It is a further object of the present invention to provide such an interlock which prevents supply of power to an electrical load center of panel from two power sources at the same time. Yet another object of the invention is to provide such an interlock which allows the switch members to both be in an OFF position at the same time. Yet another object of the invention is to provide such an interlock which is easily adaptable to commonly available switch mechanisms and electrical panels. A still further object of the invention is to provide such an interlock which is relatively simple in its components and construction and is adaptable in other switching applications.
The present invention advantageously provides an interlock for circuit breaker-type switch members installed in a standard electrical load center panel for the purpose of providing a safe and simple arrangement for providing power to the selected circuits from an alternate power source, such as a portable generator, during a utility power outage. The present invention enables the use of standard, off-the-shelf circuit breakers arranged so that their handles move in the same direction.
In accordance with one aspect of the invention, an electrical load center or panel includes a first switch mechanism including a switch member movable in a first direction, and a second switch mechanism including a switch member laterally offset or spaced from the first switch member and movable in generally the same direction as the first switch member. Both switch members are movable between an ON position and an OFF position, and may be associated with circuit breaker mechanisms which control the supply of electrical power to the electrical load center or panel from first and second power sources, respectively. An interlock mechanism is interconnected between the first switch mechanism and the second switch mechanism to prevent movement of the second switch member to an ON position when the first switch member is in the ON position. The interlock mechanism also prevents movement of the first switch member to its ON position when the second switch member is in its ON position. In a preferred embodiment, the interlock mechanism includes a support arrangement adapted for mounting adjacent the first and second switch mechanisms. The interlock mechanism includes a lever and linkage interlock assembly movably mounted on the support arrangement for pivotal movement between first and second positions. In the first position, the interlock assembly allows the first switch member to freely move between its ON and OFF positions and block movement of the second switch member away from its OFF position. The interlock assembly is movable to a second position when the first switch member is in its OFF position. When in its second position, the interlock assembly is moved into the path of the first switch member, such that the second switch member can be moved from its OFF position to its ON position and the first switch member is prevented from movement away from its OFF position. In a preferred embodiment, the first and second switch mechanisms include first and second manually operable switch handles, and the interlock mechanism is connected between the first and second switch handles.
The interlock assembly includes a first interlock member preferably in the form of a blocking lever which is pivotally mounted on the support arrangement, and is engageable with the first switch handle. A second interlock member preferably in the form of an actuating lever is also pivotally mounted to the support assembly, and is engageable with the second switch handle and movable therewith. A linkage arm interconnects the first and second interlock members. The first and second interlock members include engagement structure to prevent movement of the second switch handle to an ON position when the first switch handle is in an ON position, and to prevent movement of the first switch handle to an ON position when the second switch handle is in an ON position.
The blocking lever may be in the form of a substantially planar member having a first engagement surface engageable with the first switch handle when the first switch mechanism is in its ON position, for preventing movement of the second switch handle to its ON position. The blocking lever also has a second engagement surface engageable with the first switch handle when the first switch mechanism is in its OFF position and the second switch mechanism is in its ON position, for preventing movement of the first switch handle to its ON position. The actuating lever is formed with an opening for receiving the second switch handle. The actuating lever includes a first engagement post engageable with one side of the second switch handle, a second engagement post engageable with another side of the second switch handle and a third engagement post adapted to being engaged by the user when it is desired to move the second switch handle by moving the actuating lever. The first, second and third posts may be located about the periphery of the opening in the actuating lever.
When the first switch handle is in its ON position, application of a force tending to move the second switch handle mechanism from its OFF position causes the second switch handle to contact the actuating lever, tending to pivot the actuating lever. The force is transmitted via the linkage arm to the blocking lever, and moves the first engagement surface of the blocking lever into engagement with the first switch handle to prevent movement of the second switch handle toward its ON position. When the first switch handle is in its OFF position, application of a force tending to move the second switch handle from its OFF position causes the second switch handle to contact the actuating lever, tending to pivot the actuating lever. The force is transmitted via the linkage arm, and moves the blocking lever to a position in which the second engagement surface of the blocking lever is in alignment with the first switch handle, to enable the second switch handle to move to its ON position and to prevent movement of the first switch handle to its ON position while the second switch handle is in the ON position. The second witch handle may be directly engaged by the user for movement between its ON and OFF positions, or the user may employ the first and second engagement posts to cause movement of the second switch handle.
The support arrangement includes a mounting bracket secured to the first switch mechanism, and a base plate assembly to which the interlock assembly is mounted. The base plate assembly is supported by the mounting bracket and the first switch mechanism. A cover plate is attached to the base plate assembly and the mounting bracket in spaced relationship above the interlock assembly.
Another aspect of the invention involves an improvement in an electrical panel including a first switch mechanism having a first switch member movable in a first direction between an ON and OFF position for controlling supply of electrical power from a first source. The improvement contemplates a second switch mechanism having a second switch member movable in a direction parallel to the first direction between an ON and. OFF position for controlling the supply of electrical power from an alternate power source, and an interlock mechanism for controlling movement of the first and second switch members. The interlock mechanism includes first and second interlock members which are movably disposed upon a support arrangement interconnected with the electrical panel. The first and second interlock members are interconnected by a linkage arm which transmits motion from the second switch mechanism and the second interlock member to the first interlock member. Details of this aspect of the invention are substantially as summarized above.
The invention further contemplates a method of preventing movement of a first switch mechanism to an ON position when an adjacent second switch mechanism is in an ON position, substantially in accordance with the foregoing summary.
Various features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.